Collet



'Patented Mar. 3l, i942 UNITED STATE sA altri-:tirl carica COLLET Ossian- G.

Holmes, Riverside, It. I., assignor to Brown & Sharpe Manufacturing Company, a corporation of Rhode Island Application October 17, 19,40, Serial No. 361,491

' 1 calms. (c1. 21a- 51) This invention relates to a'collet of the type used in machine tools and is particularly adapted.

Y for the auxiliary spindle prevent Vclamp the work with equal pressure by all of a plurality'of jaws when clamping pressure is applied to the collet.

With these and other objects in view, the invention consists of certain novel features of construction, as will be more fully described, and particularly pointed out in the appended claims.

In the accompanying drawing:

Fig. 1 is a perspective view of the collet;

in the sleeve and also jaws to clamped position, all the jaws will apply equal pressure to the work for securely holding the same in the collet; and the following is a more detailed description of the presentembodif ment of this invention, illustrating the preferred means by whichI these advantageous results may 1 be accomplished:

invention is to provide v position.

A With reference to the drawing, III designates generally the collet, and II (see Fig. 6), a sleeve which'moves the 'jaws of the collet into clamping jl'he collet consists of a tubular body I2 provided with a plurality of slots, here shown as four, designated I3, I4, I and IQ, to provide a plurality of vjaws, here shown as four, consistingof the posed jaws I9 low, as at 2l, although of different bores, and the opposite jaws l1 and I8, and opslots heretofore mentioned extend from the end 22 of the body lengthwise to a point just short from the other end. The stock is such that the jaws formed are ofa resilient character, and,

' when pressure upon these jaws tending to force Fig. 2 is a sectional view through the slots of l the collet; V

Fig. 3 is an end view of the collet empty;

Fig. 4 is an end view showing in section a piece of work in the collet before clamping there;

Fig. 5 is an end view similar to Fig. 4 showing the jaws in gripping engagement with the work and the sleeve for moving the jawsto this position; and

Fig. 6 shows the main spindle in full and the auxiliary spindle in section with the work and a different position of the collet-in dot-dash lines.

It is found in certain machine tool operations and in particular in the use of screw machines having a main spindle and an auxiliary spindle' which rotate at the same speed and successively hold the work, that the usual collet which is provided in the auxiliary spindle, when moved to release its grip upon the work, permits the workto whip in the spindle. LIn order that this may be eliminated I have provided a collet havinga plurality of jaws which I have so rearranged by tempering kthem in different set positions that some of uthese jaws will maintain engagement with the work at all times although with such pressure that feeding of the work through the ljaws may be accomplished, while the other jaws,

, when released, will spring away out of contact with the work and exert no holding action upon the work whatsoever but will contact the sleeve to prevent whipping of the collet in the sleeve and I have further provided the outer surface of the jaws so that when the clamping sleeve moves the them inwardly is released, the jaws will spring outwardly to a .normalposition in which they are set by tempering.

'I'he jaws I1 and I8 are so set by tempering that their inner surfaces 23 will be closer to the central axis of the body than the inner surfaces 24 of the other -two jaws I9 and 20 when thereis no pressure applied upon the jaws. Thus, when work 25 of a certain range of diameters is inserted, the jaws I1 and I8 will be slightly sprung apart, and these will continually contact with this work, while the surface 24 of the jaws I 9 and 20 will be spaced from the same work and free therefrom. Different sized collets will be used for work of different diameters. 'I'he pressure which is applied by the resilient action alone of the jaws I1 and I8 will be such that the work may be moved by pressure to feed the work frictionally through the jaws while being continually engaged by them.

The outersurface of all of the jaws is beveled as at 26 on the jaws I1 and I8 and as at 21 on the jaws I9 and 20. These beveled surfaces are such that when their inner surfaces form a concentric circle, the beveled surfaces 26 and 21 will also be concentric. Thus, when a sleeve II 'having a female taper 3l to correspond with the beveled surfaces 26 and 21 'is forced along the surfaces 26 and 21, all of the jaws, I9 and 20 as well as I1 and I8, will be forced inwardly toward the work to grip the work with equal pressure. However, when this sleeve is moved rearwardly of the taper, the jaws I9 and 20 will and 20. The tubular body is holspring free from the work toward their normal position to which they have been previously set, and will engage the surface 3l of the sleeve to maintain contact therewith, while the jaws I1 and I8, although pressure will be relieved upon them, will still maintain a contact with the work,

although with much reduced pressure due only to the resilienceof the jaws. In this way I prevent the work from whipping in the collet and also the collet from whipping in the sleeve I I.

A chamfer for guiding the work into the opening between the jaws -is provided as at 28 on the jaws Il and .I8 and at 29 on the jaws I9 and v2li, the former chamfer being somewhat greater bular body provided with a plurality of jaws, each jaw Iprovided with Aan .inner` friction work-gripping surface and; an. outer surface to cooperate withI asleeve forthe applicationV of pressure on the jaws, somev of said jaws when being free from they-'influence ofany pressure or force having their gripping surface positioned at a greater distance from the axis of the body than other of `said jaws whereby work of certain diameters may be constantly en-gaged by some of the jaws and engaged by other of said jaws only when binding pressure is applied.

2. A collet for a machine tooll comprising a tubular body. provided with slots extending longitudinally thereof to provide a plurality of resilient jaws, each jaw provided with an inner friction work-gripping surface and an outer surface to cooperate with a sleeve for the application of equal pressure on the jaws when gripping the work, some of said jaws when being free fromv `tubular body provided with a plurality of jaws,

each jaw provided with an inner friction workgripping surface and an outer surface to cooperate with a sleeve for the application of pressure on the jaws, some of said jaws when being free from the influence of any pressure or force having their ngripping surface positioned at a greater distance from the axis of the body than other of said jaws whereby work of certain diameters may be constantly engaged by some of the jaws and engaged by other of said jaws only when binding pressure `is applied, each of said jaws being beveledat its free end to assist in guiding the work thereinto.

amaze? 4. A collet for a machine tool comprising a tubular body provided with a plurality of jaws,

each jaw provided with an inner friction workgripping surface and an outer surface to coop.

erate with a sleeve for the application of pressure on the jaws, some of said jaws when being free from the influence of any pressure or force having their gripping surface positioned at a greater distance fromthe axis of the body than other of. said jaws whereby work of certain diameters may be constantly engaged by some of the jaws and engaged by otherof said jaws only when binding pressure is applied, each of said jaws being beveled at its free end to assist in guiding the work thereinto, the jaws at the said greater distance being beveled less than the-other jaws.

5. A collet for a machine tool comprising av tubular-body provided with a plurality of jaws, each jaw provided with an vinner friction workgripping surface and an outer surface vto cooperate with a sleeve forfthe application of pressure on the jaws, some ofv said jaws when `being y free from the influence lof any pressure or'fo'rce having their gripping surface positioned' at a greater distance from the axisof kthe body than other of saidjaws whereby worl;` of certain diameters may be constantly engaged by 'some of the ,jaws and engaged by. lother of said Ajaws only when binding pressure is applied, 4the pressure of the jaws constantly engaging the work being -such that the work may be fric'tionally fed therethrough. c

6. A collet for a machine tool comprising a to engage the same as to cause the application'- of equal pressure on the jaws, two of said jaws when being fre'e from' the influence of any pressure or force having their gripping surface positioned at a greater distance from the axis ofthe body than the other two of said jaws whereby Work of certain diameters may be constantly engaged by two of the jaws and engaged by the other two of saidjaws only when binding pressure is applied. l

7. In combina-tion, a machine'tool sleeve, a collet within the sleeve comprising a tubular body provided with a plurality of jaws each jaw provided with an inner friction work-gripping surface and an outer sleeve-engaging surface upon which pressure is applied tothe jaws, some of' said jawswhen being free from the influence of any pressure or force having their sleeve-engaging surface engaging the sleeve, and other of said jaws free from the sleeve and positionedinwardly sufliciently to engage the work, whereby work of certain diameters may be constantly engaged by some of the jaws and engaged by other of said jaws only when vbinding pressureis applied by relative movement of rthe sleeve x.whereby whipping of the collet in the sleeve and 

